However I wouldn't be too keen about passing carb and brake cleaner through that little valve, I'm pretty sure it would have a small butyl rubber seal which would not take kindly to that harsh a clean. Even WD40 overnight...

I remember troubleshooting mine once, after installing a new charcoal cannister I wanted to verify it was ok. I figured that closed one way (NC) without power in direction of the arrow was normal, and that with power it opened so test was good. It was for sure the original valve from factory on a euro 10/88 M30B35. Oh, and it was running 100%, no idle hunt.

Have you tried disconnecting the ICV, O2 sensor and the AFM? If it idles ok missing one, perhaps that is the culprit? Is the ICV working nice, smooth and free? Is the TPS clicking closed when @idle? (Not sure how this translates to a EML/fly by wire setup, or whether it has a TPS or some other feature.